Full Transcript Turmeric Evidence Overview 0:00 Doesn't it seem like when it comes to nutrition, there are more opinions than 0:04 facts to go around? Every day we hear new [music] theories 0:08 about diets and supplements and best foods to eat. Well, my role is to take 0:13 the mystery out of good nutrition and look at the science. Welcome to episode 0:19 500 of the NutritionFacts podcast. In our first story, we look at dozens of 0:24 human trials that reveal where turmeric delivers and where it doesn't. With 0:30 [music] our former senior research scientist, Dr. Kristine Dennis. 0:34 The number of clinical trials on turmeric, not in rats or petri dishes, 0:38 but with actual people, continues to climb, 0:41 dozens a year. And most were randomized double-blind 0:45 placebo-controlled, the gold standard for clinical trials. 0:49 There have been so many trials published that there are now umbrella reviews on 0:53 turmeric. You've heard of systematic reviews and 0:56 meta-analyses, pooling multiple studies together. 0:59 Well, an umbrella review can be like a systematic review and meta-analysis of 1:03 systematic reviews and meta-analyses, meaning pooling multiple meta-analyses 1:08 together, placing them at the very top of the hierarchy of evidence pyramid. 1:13 Dr. Greger has covered the benefits of the turmeric pigment curcumin for knee 1:17 osteoarthritis, in some cases working as well as or even 1:21 better than anti-inflammatory drugs and painkillers, without their side effects 1:25 of injuring our gut. And in the 10 years since, a 1:29 meta-analysis of 11 meta-analyses on the efficacy of curcumin for relieving 1:33 osteoarthritis strongly supports that it can relieve pain as well as improve 1:38 joint mobility and shorten medication use. 1:41 And more isn't necessarily better. Low-dose extracts appear to have similar 1:46 pain relief effects to high-dose extracts. 1:49 What about other arthritic conditions? A pilot study in 2012 of 45 patients 1:55 showed promise for rheumatoid arthritis, finding it is actually more effective at 1:59 alleviating pain compared to the leading drug. 2:02 And a recent meta-analysis including more than 500 patients found the same. 2:06 Curcumin was beneficial both for inflammation levels and clinical 2:10 symptoms. Curcumin's ability to lower some 2:13 inflammatory biomarkers like C-reactive protein, a marker of systemic 2:17 inflammation, extends more broadly to patients with auto-inflammatory 2:21 conditions, and the stronger effects seem to appear at relatively smaller 2:26 doses. You may recall that Dr. Greger talked 2:29 about a 2012 study in pre-diabetic individuals, where 0% of those taking 2:34 curcumin extract for 9 months progressed to type 2 diabetes, while 16% of those 2:39 on placebo did. There have been a lot of studies since. 2:44 14 systematic reviews and meta-analyses containing 61 individual randomized 2:49 controlled trials were included in this umbrella review.
Turmeric for Blood Sugar, Cholesterol, and Weight 2:53 Fasting blood sugars and HbA1c, a measure of longer-term blood sugar 2:57 control, both improved, no matter what formulation of turmeric 3:01 or curcumin was consumed. But, the quality of the studies was low, 3:06 not including important information like their funding sources. 3:10 And the types of turmeric curcumin preparations were wide-ranging. 3:15 What if we want to know the impact of turmeric alone, not a special curcumin 3:19 formulation that supplement companies can charge us a bunch of money for? 3:24 This dose-response meta-analysis breaks it out for us, with turmeric resulting 3:27 in better results than curcumin-only treatments. 3:33 Note the benefit was found for a variety of participants, not only those with 3:36 diabetes. What about cholesterol? Here's another 3:40 umbrella review. Although the authors concluded that 3:43 curcumin could have ameliorating effects, there was only a half-point 3:47 drop in LDL. Lower doses may work better, but a 3:51 two-point drop is still nothing to write home about. 3:54 Turmeric curcumin blocks obesity in mice fed a high-fat diet. 3:59 What about people? In an umbrella review of 50 randomized 4:02 controlled trials, curcumin supplementation significantly decreased 4:06 BMI, body weight, and waist circumference. 4:10 It was significant statistically, but how much of a difference did it really 4:14 make? A loss of about a half kilogram or a 4:18 little more than a pound of body weight. Waist circumference, a measure of 4:22 abdominal obesity, decreased by about a centimeter, and triple the effect in 4:26 trials with whole turmeric relative to curcumin extracts. 4:31 So, for those with obesity or type 2 diabetes and wanting to lose weight, 4:35 the primary prescription is lifestyle modification. And some turmeric on the 4:39 side might be helpful, but may not make that much difference. In our next story, 4:43 we look at what happens when turmeric is put to the test to reverse DNA damage 4:49 caused by arsenic exposure. Arsenic is a carcinogenic heavy metal, 4:55 and the major mechanism of arsenic-related damage appears to be 4:59 oxidative stress. It's the arsenic-induced accumulation of free 5:03 radicals that can kill off cells and damage our DNA. 5:07 And then the double whammy is that it may disrupt our body's ability to repair 5:12 our DNA once it's damaged. Well, if the damage is oxidation, what 5:17 about eating an antioxidant-rich food such as the spice turmeric, which 5:22 contains an antioxidant pigment known as curcumin? 5:25 As anyone familiar with my videos can attest, numerous clinical trials have 5:29 suggested therapeutic efficacy against a variety of human diseases including 5:34 cancer, diabetes, Alzheimer's, and inflammatory bowel, joint, lung, skin, 5:38 and eye diseases. In terms of protection against heavy metals, they suggest 5:44 turmeric may both help scavenge free radicals as well as chelate or bind up 5:49 heavy metals. But, it's all just theory 5:52 until you put it to the test. Unfortunately, until recently, the tests
Turmeric Against Arsenic DNA Damage 5:58 were like where you can see if curcumin can protect against heavy metal-induced 6:02 oxidation in pureed rat brains. Why can't you just give some turmeric to 6:07 people? It's not like there aren't millions of people out there who've been 6:12 exposed to arsenic and could use some help. 6:16 In what became the greatest chemical disaster in human history, so-called 6:20 tube wells were installed in Bangladesh to provide clean water. UNICEF meant 6:25 well. Too bad they didn't test the water for 6:29 arsenic. As many as one in 10 in some parts of the country will now go on to 6:33 die from cancers caused by the arsenic exposure. 6:37 This allowed the medical community to document all sorts of interesting 6:41 cancers, but why not give them something that may 6:45 help like turmeric curcumin? After determining the extent of DNA 6:51 damage, 50% of volunteers were randomly selected and prescribed curcumin 6:55 capsules blended with little black pepper compound, and the other half were 6:59 given a placebo. Now, they wanted to establish a baseline 7:03 in the arsenic-exposed group, so they waited for 3 months to start the study. 7:08 And indeed, the DNA damage remained stable. 7:11 Then for 3 months, they proceeded to give them the curcumin or the placebo. 7:15 The placebo didn't do much, but within the first month, you could see the 7:20 curcumin working. And by the third month, the DNA damage in the 7:23 curcumin-treated arsenic group was no worse than those who hadn't been exposed 7:28 to arsenic at all. That's amazing. The curcumin had an effective role in the 7:33 regression of DNA damage. Yes, it's an excellent antioxidant 7:38 agent, but what they found subsequently is that the curcumin undid the arsenic 7:43 crippling of our DNA repair enzymes. So, both help prevent the damage and 7:48 facilitate repair. Thus, curcumin may be a useful modality 7:52 for the prevention of arsenic-induced cancer development. 7:57 Of course, you have to make sure the turmeric itself isn't contaminated with 8:00 heavy metals. All those poor kids in Bangladesh. 8:04 It's not one thing, it's another, and it's not just kids in Bangladesh. Nearly 8:08 a quarter of spices purchased in Boston had lead in them. 8:13 It's not just a matter of buying US versus foreign brands, as the lead 8:17 levels were not found to be statistically significantly different. 8:21 How about just eating antioxidant-rich fruits and vegetables? 8:25 The reason we care about DNA damage is that we care about cancer. What if you 8:30 measured the beta-carotene levels in people exposed to arsenic who went on to 8:34 develop cancer compared to those who got exposed to the same amount of arsenic, 8:38 but didn't get cancer? Beta-carotene is like a proxy for healthy fruit and 8:43 vegetable intake. The way you get high levels in your blood is you eat lots of 8:47 healthy foods like greens and sweet potatoes. 8:50 Compared to those with low levels, those with high [snorts] levels of 8:53 beta-carotene in their blood had 99% lower odds of getting arsenic-induced 8:59 cancer, 100 times lower odds. So, if you're going to eat rice, why not 9:05 some rice with some sweet potatoes on top? Finally today, an unsettling number 9:10 of cases linking turmeric extract curcumin supplements to liver injury. 9:16 Liver injury associated with turmeric, 10 cases from the drug-induced liver 9:20 injury network in the United States. And there are others, too, including three 9:24 cases reported in Australia and a series reported to the Italian Ministry of 9:28 Health. Is turmeric really a new hepatotoxic substance? First of all, 9:33 regardless of what the titles of the papers say, 9:36 these cases appear to be from turmeric extract supplements rather than turmeric 9:40 the spice. It's like green tea and green tea 9:44 extract pills. Brewed green tea appears to be 9:47 completely safe for the liver, but give people green tea extract supplements, 9:51 and the livers of as many as one in 17 people becomes inflamed. So, we should 9:55 consume our green tea in beverage form, not pill form. And similarly, our 10:00 turmeric in spice form at culinary doses, not capsules. Unless they contain 10:05 just a single ingredient, whole spice turmeric, not curcumin, not an extract, 10:10 no other ingredients. While turmeric extract supplements have a relatively 10:14 safe side effect profile even at high doses, there is an increasing number of 10:18 case reports linking them to liver injury, especially when combined with 10:22 agents such as piperine, a compound found in black pepper. 10:26 As we've covered before, compounds like piperine are added to turmeric to 10:29 enhance the bioavailability of curcumin, potentially contributing to its 10:33 toxicity. As one reason curcumin may be so safe is that it's poorly absorbed. 10:39 As we have cautioned before, piperine blocks liver detox enzymes that can make
Turmeric Safety, Liver Injury, and Contamination 10:43 some substances like curcumin more potent. 10:46 And turmeric curcumin supplement formulations with high bioavailability, 10:50 such as nano formulations or those with added piperine, 10:54 have been less investigated. There's a mistaken assumption that if a 10:57 little is good, then more must be better. 11:00 We'd never make that assumption for drugs, so why is it made for 11:03 supplements? In this case, more does not necessarily 11:08 mean better. A review of nearly a hundred randomized controlled trials of 11:12 turmeric or curcumin supplements for non-alcoholic fatty liver disease found 11:16 that they successfully calmed liver inflammation and guess which worked 11:19 better. Low-dose supplements worked about 10 11:22 times better than high-dose ones. There are caveats though, even for whole food 11:27 turmeric. As Dr. Greger has covered before, 11:30 people who have a tendency to form kidney stones should be careful due to 11:33 turmeric's relatively high oxalate content. 11:36 Dr. Greger recommends only a quarter teaspoon a day in his daily dozen. 11:40 There's also been concern about lead contamination of the whole food spice. 11:44 Lead chromate has been used to make turmeric appear more yellow in 11:47 Bangladesh, where much of turmeric sold in the United States is imported from, 11:51 leading to multiple recalls. The wonderful news is food safety 11:55 policies can work. Since the original paper of lead chromate contamination in 11:59 turmeric from Bangladesh, the portion of market turmeric samples with detectable 12:03 lead went from about 50% to zero. Unfortunately, there is still more work 12:09 to be done though. In four South Asian countries, where 12:12 more than 80% of the world's turmeric is produced, 14% of samples had detectable 12:17 lead above 2 micrograms per gram. For context, this is 20 times higher 12:22 than the US Food and Drug Administration's maximum allowable level 12:26 for lead in candy. And some stores sold turmeric containing 12:30 much higher levels of lead that would result in projected blood lead levels in 12:34 children up to 10 times higher than the US Centers for Disease Control's 12:38 threshold for concern. This is a reminder that just because something is 12:42 natural doesn't mean it can't cause harm. Turmeric dietary supplements are 12:45 big business, estimated to account for $69 million in sales in the United 12:50 States alone. Though it's popularity does help put the recent spate of liver 12:54 toxicity cases in context. More than 10 million people in the United States take 12:59 turmeric or curcumin supplements, so that would be like one case in a 13:02 million. Some people may just be more susceptible 13:07 genetically. Seven of the 10 patients in this case series had a genetic variant 13:11 that's relatively rare in the general population. 13:14 Still, it's safer for everyone to use the real thing and not some extract in 13:19 some supplement. And please don't let anyone inject 13:23 turmeric or curcumin into your veins. Visit nutritionfacts.org/audio 13:28 to see all the podcast episodes with descriptions that include links to the 13:32 associated videos. Sources cited and other details are available on each 13:36 video's page. Information about my books, How Not to Die, How Not to Diet, 13:40 and [music] How Not to Age, is at nutritionfacts.org/books. 13:44 All proceeds, of which I get, are donated directly to charity. And I've 13:49 got a new book in the publication pipeline, the manuscript for How Not to 13:53 Hurt, my diet and lifestyle approaches to pain management. It's been handed in 13:58 and will be published December 15th. >> [music] 14:01 >> I'm going to be doing a series of webinars to feature some of the new 14:04 research that I discovered. Sign up for our free newsletter at 14:08 nutritionfacts.org/subscribe to stay updated on when those will be. 14:14 Nutritionfacts.org is a science-based nonprofit and everything on the website 14:18 is free. There are no ads, no corporate sponsorships, [music] no kickbacks. 14:22 We're strictly non-commercial, not selling anything. I just put up as a 14:25 public service, as a labor of love, as a tribute to my grandmother, whose own 14:30 life was saved with evidence-based nutrition. We just have like a 14:34 a Wikipedia-type nonprofit model where everything's free and we just hope 14:38 maybe, you know, one of a thousand people will find it so valuable that 14:42 they'll kick in a few bucks so we can continue to churn out new content 14:45 >> [music] >> to help you and your family be 14:48 healthier. Thanks for listening.
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